Question

which trig function do you use? tangent sine cosine

Explanation:

Step1: Recall trigonometric function definitions

• Sine: $\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}$
• Cosine: $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$
• Tangent: $\tan\theta=\frac{\text{opposite}}{\text{adjacent}}$

Step2: Identify sides relative to the given angle

• Given angle $\theta = 40^{\circ}$, hypotenuse $= 19$, and we need to find the side $x$ which is opposite to the $40^{\circ}$ angle.
• Using the sine function definition $\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}$, here $\theta = 40^{\circ}$, opposite side $=x$, hypotenuse $=19$.

Answer:

Sine